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Fire in submarine: seven minutes to evacuate, two minutes to dress

Mumbai, Feb. 26: Two young officers of the Indian Navy choked to death after they were trapped inside a submarine compartment that was flooded with toxic gases to extinguish a fire on board.

The two officers have been identified as Lieutenant Commander Kapish Muwal and Lieutenant Manoranjan Kumar.

The commanding officer of the submarine is among 29 other sailors and technical staff aboard the INS Sindhuratna, a Russian-built submarine, who are receiving medical aid after inhaling the gases.

The Sindhuratna, a Kilo-class submarine, had embarked on a Task 2 mission under Commodore Commanding Submarines (West) S.K. Kapoor to check whether the recently refitted vessel was fit to be deployed at sea. The Task 1 inspection mission had earlier certified it harbour-worthy.

The submarine belongs to the same class as the INS Sindhurakshak which was destroyed by an ordnance implosion in its missile compartment in August 2013 while being anchored at the Mumbai harbour. As many as 18 sailors had died in that accident.

This morning, around 6, an alarm went off aboard the Sindhuratna when it was about 100 nautical miles from the Mumbai harbour.

“The inspection team was at work at the time and though the alarm signified some problem in the battery pit, some sailors and officers initially did not take it seriously. They thought it was a simulated alarm set off by the inspection team,” said a naval source.

There is a set protocol by which the crew operates in submarines. In case of any exigency in the battery pit, the commanding officer of the submarine issues a series of parallel orders to ensure safety of the crew and the vessel.

In line with protocol after the alarm went off, a crewmember was sent to open the hatch of the battery pit slightly to check if there was a fire.

When he confirmed, the commanding officer ordered immediate isolation of compartment 3 so that fire-extinguishing gas could be sprayed in the compartment.

The hatch between compartment 3 and 2 had already been closed by then to aid isolation of compartment 3.

“The evacuation of crew from compartment 3 to 4 began. Everybody had to grab their IDA suits and move out to the engine room,” said the naval source.

An IDA set is a breathing apparatus consisting of a mask, suit and oxygen cylinder used by submarine crew in emergencies like a gas leak or a fire.

“When the evacuation was ordered, many of the men were sleeping and some officers were hanging around in the galley where the kitchen is located. A bit of a time lost as people did not take things seriously at first, believing them to be part of an inspection drill and not a real emergency,” said the navy source.

By the time crew members started rushing into compartment 4, the gas from the fire-extinguishing sprays which are activated from the main control room had already engulfed compartment 3 and started moving into compartment 4.

“The gases in the submarine fire-extinguishers — a deadly cocktail — are lethal but they do not kill immediately. There is a 7-to-8-minute window after the spraying starts during which one can get into the IDA suit and start breathing oxygen from the cylinder. Since getting into the suit is a two-minute affair for all crewmembers, 7 to 8 minute offer a pretty large window to escape the effects of the gas,” said the naval source.

When it was found that the sprayed gases were spilling into compartment 4, the crew were evacuated into compartment 5 and the hatch between compartment 4 and 5 was closed down.

The entire process usually takes 3-5 minutes. Immediately after compartment 3 was isolated and evacuation over, a headcount began.

“Soon it became clear who the missing personnel were and it was feared that they might have been stuck in the toilet of the sub or late in stepping out of the compartment before the hatch closed,” said the naval source.

By then, the submarine had been raised to the periscope level and then to the surface level. “After a battery accident, a submarine is quickly brought to the surface to recharge it using diesel engines. This happens at periscope level so the exhaust from the diesel can be pumped out. In the case of a fire, the submarine has to be brought to the surface so the snort mast can be raised,” said the navy source.

The snort mast is a pipe through which the toxic gases from fire extinguishers are expelled into the air and fresh air is channelled inside the submarine.

Submarine commander Sandeep Sinha opened compartment 3 after the snort mast had expelled some toxic fumes and went in with some men in search of the two missing officers. Sinha and his men, who breathed in the foul gases, took ill. A doctor on board was also affected by the gases.

“Help was sought to take the sub and its crew ashore but then luck was not on our side,” said the source. With a critical naval exercise on way in the Bay of Bengal, there were hardly any naval ships available. The ones which were deployed on the western shore were far from the Sindhuratna.

A helicopter was rushed from the Mumbai base, which airlifted seven critical crewmembers to the naval hospital, INS Ashwini.

About two hours later, two ships reached the Sindhuratna. The other affected personnel, including Sinha, were evacuated to the shore.

The bodies of the officers were airlifted in the evening to the naval hospital.

The Sindhuratna is expected to reach the Western Command Naval docks by Thursday afternoon.

Ten Kilo-class submarines were procured from the USSR/Russia between 1985 and 2000. The Sindhuratna —fifth in the series — was commissioned in November 1988 in Russia’s Nizhny Novogorod. It went through a short refit at the naval dockyard in Mumbai for six months ending December 2013. The submarine was not armed at the time of the mishap.